The present invention relates to an apparatus for removing foreign substances in gas, such as a dust collector for removing particulates from exhaust gas.
During processes of manufacturing optical fibers or silicon wafers, particulates of SiO.sub.2 and other substances are mixed with exhaust gas. In the manufacture of semiconductors by the chemical vapor-phase deposition or the like, powdery mists of Sb, B, As, Ge, etc., exist in exhaust gas. When refining aluminum, metal dust of aluminum or the like is mixed with exhaust gas.
Conventionally, these particulates in exhaust gas are removed by means of dry-type dust collectors, such as centrifugal dust collectors, electric dust collectors, etc., or wet-type dust collectors, such as Venturi scrubbers, etc.
These prior art dust collectors, however, are subject to a defect such that their collection efficiency is low for particulates with the particle size of 10 .mu.m or less. Moreover, they entail high equipment costs and require complicated maintenance work. The Venturi scrubbers, in particular, suffer so great a pressure loss that they consume considerable electric power. Thus, they require a large-sized power source, which is expensive.